...and all from the script. That's because this isn't a sequel, it's... more like an overgrown tongue-in-cheek fan-fic film that just happened to lure Singer in for the ride.
There's a lot to laugh at here, and unfortunately the "plot" is most of it. The players are fairly game and give some effort to their portrayals, but the writing just is never serious. Sadly, sometimes it pretends to be, but always returns to campiness before long. The dialog is very dated, too, as others have noted. Prepare to wince.
Taken for what it is -- cheesy, spoofish fun -- it actually isn't too bad, IMO. 4/10 for being brisk enough to carry me along to the end and make at least a few actually funny jokes. (My favorite was the line about the 2 guys she'd met in Mexico.) Kari's character annoyed me a lot at first but she got better later. Wings actually surprised me; I thought he made a serviceable villain (at least for this sort of camp), and I was expecting him not to fit well. Then again, I was expecting a real sequel....
One thing that needs pointing out is that Lyranna vanishes near the end of the film. The character just isn't seen any more, with no explanation of what happened to her. Oops.
So... If you don't allow it to be what it is and instead hold it up to the first movie, it stinks, as most reviewers have pointed out. If you're going to watch it, don't make that comparison. Just mostly forget the first movie, relax, and laugh at the intentional and unintentional humor here. Throw stuff at the TV when the cheese gets too thick. That way you should be able to enjoy it well enough.